Anyone tried 6.8X51/.277 Fury hybrid cases?

[omega1]

Has anyone used the Sig hybrid .227 Fury case to form any other round? I'm thinking .260 Improved but don't know if this is a practical endeavor. I just ordered 100 cases from American Reloading and trying to decide how to go forward with the most practical approach. I shoot .308, .260, .260 Improved and 7mm08 in that basic format. I've heard it can be difficult to full length resize the hybrid case.

 

[FrankG]

The cases on the American Reloading website just shows a standard brass case.

When you say hybrid cases you mean the steel case head case correct?

So if that is so... what's your intent on using the steel case heads for? Last I heard that hybrid case and or ammo isn't suppose to be available to the public.

The standard ammo / full brass case is what will be available and it's loaded to standard working pressures. Not the 80k psi pressures of the hybrid case/ammo.

Later, Frank
Bartlein Barrels

 

[omega1]

From their site today

 

[Just Say Moe]

It looks like they are pull downs so the steel part won't need resizing? Once they have been fired though- who knows? Maybe one and done? Also says they are full of of stuck powder.

 

[Walt Krafft]

I have played with versions in 6, 6.5, 270, and 7mm. Performance with the hybrid case is greater than the equivalent sized brass case, as it should be at the higher pressure. But, a larger case such as a WSM or 284 will get the same performance as the hybrid case. The hybrid case does not show pressure like we are used to so you could vastly exceed safe pressure levels without some method of measuring pressure. Where is the weak link after the case? Resizing is a real issue. The steel head does not spring back like a brass case so extraction can be a problem in non-chrome plated chambers.
IMO, it is an excellent solution for the situation it was designed for. Is it the next super duper cartridge for sporting use? No. Other existing cartridges can yield equivalent performance.

 

[omega1]

Thanks Walt. My ambitions are modest. I would like to get 3000 fps from a .260 Improved using a 140 gr. bullet without any issues. This would give me 6.5 PRC performance and hopefully give me a long working life on the brass. What did you observe in your 6.5 version? I also like the idea of getting more velocity safely out of the 7-08.

 

[Walt Krafft]

What part of the steel head does not spring back like brass are you not understanding? You want 3000fps with a 6.5 140gr bullet, get a 6.5x284.

 

[JLT]

Thanks Walt. My ambitions are modest. I would like to get 3000 fps from a .260 Improved using a 140 gr. bullet without any issues. This would give me 6.5 PRC performance and hopefully give me a long working life on the brass. What did you observe in your 6.5 version? I also like the idea of getting more velocity safely out of the 7-08.

You can get 3,000 fps out of a 140 with RL-23 in a .260 AI. Start at 46.0 gr. and work up in .3 gr. increments and you'll get there soon enough. I exceeded 3,000 fps (stopped at 3,053 fps) safely out of a 28" barrel. Your brass won't last forever, but I got a good ten-twelve cycles out of it (Lapua) before the primer pockets started loosening up.

 

[omega1]

I understand perfectly. I own a 6.5-284 and a 6.5 PRC but the experimenting and testing is an attraction. Do you understand?

 

[Walt Krafft]

I understand perfectly. I own a 6.5-284 and a 6.5 PRC but the experimenting and testing is an attraction. Do you understand?

Yes, completely. Just trying to save you time, money and frustration. I own the t-shirt.

 

[FrankG]

To add what Walt is saying….

The steel case head will start to ring the chamber after X amount of rounds at high pressure. I’d give you about 250-500 rounds and you will start to have extraction issues. Serious issues.

Also running it at high pressure on standard bolt guns… be prepared to use a dead blow hammer to open the bolt not just on the uplift but beating it back as well.

Also copper fouling will be an issue and effecting accuracy. To hold good accuracy you will be cleaning it about every 30 rounds.

Walt can correct me if I’m wrong but if I am… I’m not far off.

I have to agree with Walt… right now for the intended purposes of a military round with purpose built guns for that round is where it’s at and not for casual or target shooting in conventional guns.

Later, Frank
Bartlein Barrels

 

[FrankG]

This is also my stance on this and I’ve instructed all my guys in the office the same thing several months back.

Until I see more data/information and using this as a high pressure round…

We won’t do any barrel installations in this caliber. The only barrels we are making for this caliber are strictly for ammunition/bullet testing for gun manufacturers and for R&D. We will not do any for the general public.

If a customer buys one of our barrels and goes down this road to play with this round and tells us that on the phone etc… this is what we tell them.

I/we warranty no barrel. Not for fouling, not for accuracy and not for barrel life or damage to the firearm or for safety.

Go on the Saami website and look it up. In a yellow box it says:

WARNING:
Maximum Average Pressure levels greater than 65,000 psi may present increased risk of unsafe cartridge case or firearm rupture and thus require cartridge case and/or firearm designs that depart from traditional practices (materials, construction, and other design criteria).

 

[ronemus]

In addition to the case, primers that will withstand the higher pressures routinely are needed. I have enough issues with primers at conventional pressures that I wouldn't trust them in this application. I somebody selling the primers .mil uses on the open market?

 

[Walt Krafft]

FrankG is spot on. I didn't get into and won't get into some of the things that need to be done to the rifles for the hybrid cartridge. The high pressures take special precautions to keep the genie in the bottle. This is the equivalent of putting nitomethane into your Mustang's gas tank, you may set a new record in the quarter mile, but you are more likely to leave a big oil slick at the starting line.

 

[CJ6]

I just like the idea of a factory 270-308. Long overdue in my opinion.

 

[omega1]

Anyone that has an interest in this topic there is a bunch of excellent information on Len Backus' Long Range Hunting site.

 

[jfjohn77]

"Mike D Texas" over on Long Range Hunting has been messing with the cartridge resized to 260AI for some time now. I'm looking at it for an AR10, since that was what it was designed for, just not at 80,000psi. Sig has already lowered that to 70,000psi, due to what they called accuracy issues. Most likely bullet stability.

 

[Walt Krafft]

Please be aware that Sig does NOT use the AR10 gas system. It took lots of engineers and developement to safely handle the extra pressure. And, you have no way to know the pressure without a pressure test barrel. Be carefull!

 

[jfjohn77]

Please be aware that Sig does NOT use the AR10 gas system. It took lots of engineers and developement to safely handle the extra pressure. And, you have no way to know the pressure without a pressure test barrel. Be carefull!

Yes Sir, thanks for your warning and this is not meant to offend in any way, but I have been running AR platforms since the Marine Corps first handed me an M16 in 1972. I have built too many to recall for myself, family and friends. And I am well aware that the Sig XM7 is a piston driven gas operated system and not the usual/older direct impingement system. The piston driven gas operated system has been in use for several years now, and readily available. It is adjustable for gas pressure/volume, just as the direct impingement system is when using an adjustable gas block.

 

[Straightshooter1]

As a tinkerer, I just have to play with these hybrid cases.

Went out last week and fire formed 10 hybrid .308 cases with case volume of 56.3 grs H2O and loaded them with 41.7 grs IMR-4064 behind 190 SMK's using the same primers that I removed from them and seated the primers to the same depth as they were originally. Though this was only to fire form them to I could measure their case volume after firing, the chrono data was remarkably good. SD for the 10 shots was 4.7 and the ES was 15 with MV at 2,560 fps from 26" barrel. Group size was surprisingly good too at .552 MOA.


Sorted through my 4 remaining boxes to see how many of the different head stamps there are and found 4 different headstamps (stamps were like "24", "23" "Sig" and "277 Fury"), each having different case weights. The cases I loaded above were the 24's and the heaviest of them all and was with majority of them all. The 23's were very close to the same, just a little lighter. Those with the "277" Furry stamp were all much lighter and I expect a substantial increase in case volume and since there was about 75 of them, I processed them into a .308 case and loaded some up to fire to form next using the same powder (10 with 190 SMK's and 10 with 168 SMK's). Will see how they compare. :giggle:

Finally got out to fire these ^^^^^ and collect the data:

168 SMK's
46.0 grs IMR-4064
Case Fill: 101.9%
COAL: 2.870
Case Volume: 57.7 gr H2O
Ambient Temperature: 94°F
AVG MV: 2,859 fps
SD: 6.7, ES: 25
QL Estimated Pmax pressure: 69,733 psi

190 SMK's
43.4 grs IMR-4064
Case Fill: 100.2%
COAL: 2.885
Case Volume: 57.7 gr H2O
Ambient Temperature: 94°F
AVG MV: 2,657 fps
SD: 12.7, ES: 35
QL Estimated Pmax pressure: 64,230 psi

All cases extracted normally with no bolt lift issue; no pressure signs. Actual case volumes of fired cases weren't known until after these were fired. The 57.7 gr of H2O is exactly what I've had with Winchester brass and at 2 grs more than my Lapua brass. The hybrid cases with head stamp of "24" were 1.4 grs less in case volume, which was expected when weighed and being heavier.

Upon taking some case measurements, I wasn't expecting as much expansion of the area at the .200 area of these hybrid cases as I found. I thought the steel would retain most of it's starting dimensions. As it turns out, that area of the case grew from .467" to .470. The fired cases still easily chambered and extracted. My Lapua cases expand from .469" to .4705" (they've been fired 11 times so far and are till in very good condition; virgin Lapua cases start at .468").

WARNING: Playing above SAAMI max pressures can be dangerous and shouldn't be attempted by those having little experience!